Edit

SYSLIB0018: Reflection-only loading is not supported and throws PlatformNotSupportedException

  • Article

The following methods are marked as obsolete, starting in .NET 6. Calling them in code generates warning SYSLIB0018 at compile time. These methods throw a PlatformNotSupportedException at run time.

Workarounds

Reflection-only loading is replaced by the metadata load-context in .NET Core and .NET 5+. For more information, see How to: Inspect assembly contents using MetadataLoadContext.

Suppress a warning

If you must use the obsolete APIs, you can suppress the warning in code or in your project file.

To suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the warning.

// Disable the warning.
#pragma warning disable SYSLIB0018

// Code that uses obsolete API.
// ...

// Re-enable the warning.
#pragma warning restore SYSLIB0018

To suppress all the SYSLIB0018 warnings in your project, add a <NoWarn> property to your project file.

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   ...
   <NoWarn>$(NoWarn);SYSLIB0018</NoWarn>
  </PropertyGroup>
</Project>

For more information, see Suppress warnings.